Reaction of hydrocarbons



May 2, 1944. o. N. MILLER REACTION OF HYDROCARBONS Filed Oct. 13, 19395E2: a m p as/58 v 2 3 m; 1 Mm INVENTOR ZQQNEWESQ OTTO N. MILLERPatented May 2, 1944 REACTION OF HYDROCARBONS Otto N. Miller, ElSegundo, Calif., assignor to Standard Oil Company of California, SanFrancisco, Calif., a. corporation of Delaware Application October 13,1939, Serial No. 299,289

This invention relates to an improved process for the production ofmotor fuels of high antiknock value from hydrocarbons containing morethan two and less than six carbon atoms per molecule and, moreparticularly, to a process wherein relatively light hydrocarbon mixturescontaining olefins and isoparaflins are subjected to polymerization andalkylation reactions in a manner to produce high yields of liquid motorfuel of high quality.

The catalytic polymerization of normally gaseous'olefin containing fromtwo to five carbon atoms per molecule such, for instance, as result fromthe cracking of petroleum oils or the dehydrogenation of fractions fromnatural gas, by means of catalysts comprising or derived from sulfuricor phosphoric acids has resulted in materially a'ugmenting the availablesupply of motor fuel, and particularly fuel having higher than averagenondetonating value. When the polymers so produced are saturated byhydrogenation, they provide excellent raw material for the preparationof superior aviation motor fuels.

It has also been disclosed that the'isoparafilnic hydrocarbons, such asisobutane and isopentane, may be caused to react with the normallygaseous olefins, such as propylene and the butenes, by means of liquidacid catalysts, such as concentrated sulfuric acid. In its simplestexpression this reaction results in the addition of a single olefinmolecule to a molecule'of the isoparaflin with the production of a newisoparaflln molecule containing a number of carbon atoms equal to thesum of those in the original olefinand isoparaflin. This reaction isherein referred to as one of alkylation and the products thereof asalkymers. The alkymers produced from the isoparaffins containing lessthan six carbon atoms per molecule and the normally gaseous olefins havea high antiknock value and are therefore suited for use in thepreparation of aviation motor fuels.

Both the polymerization of gaseous olefins and the alkylation ofisoparafiin by olefins are thus particularly applicable to theproduction of motor fuels of h gh octane number and have been foundespecially useful in the production of such fuels from the lighthydrocarbon mixtures resulting from the cracking of petroleum or thepartial dehydrogenation of fractions from natural gas. Fuels of thehighest octane number are at present produced for use in aviation motorsand are thus limited by the high volatility requirements of such serviceto an end point such that little or no material boiling above thenonanes may be in- 7 Claims. (Cl. zoo- 83.4)

eluded. The so-called C4 cut" from the cracking reaction is thus atpresent the most readily available and generally satisfactory rawmaterial from which to produce such superior fuels by either alkylationor polymerization. Neither such reaction will, however, alone convertmore than about half of a C4 cut of usual composition into liquid motorfuel, and a more eflicient utilization of the available raw materialthan is provided by either is thus much to be desired.

In one method which has been proposed for effecting the foregoingalkylation reaction, the isoparafiin and olefin reactants are intimatelycontacted in the presence of a liquid sulfuric acid catalyst and thealkymers formed thereby are separated from the catalyst and fromunreacted raw material by any appropriate means.

In another specific method for alkylating isoparaffins with olefinsadvantage is taken of the discovery that the alkylation of anisoparafiin by an olefin, in the presence of a strong acid of the natureof sulfuric acid, is not a single reactionbut is in fact the sum of twoentirely distinct reactions which may therefore be separated and Y eacheffected under the conditions best suited to it with considerableimprovement in operation and in the product obtained. a

The two separate reactions which result in the alkylation ofan'isoparaflin by an olefin in the presence of a strong acid of thesulfuric acid type are: first, the alkylation of the acid by the olefinto form what is for convenience referred to herein as an alkylated acid"solution containing free acid, some of the alkyl acid ester of the acid,some polymers and apparently some as yet unidentified compound betweenthe acid and the olefinv or a polymer or other reaction product thereof,and second, the reaction of the alkylated acid solution thus producedwith the isoparaflin to form an alkyl isoparatfin or alkymer and, withthe isoparaifin in substantial excess, to release the acid approximatelyas it was before the alkylation.

It has been found that the conditions best suited to the acid alkylationstage are not the same as those for the hydrocarbon alkylation stage andthat the maximum benefits that may be derived from conducting thealkylation reaction in two separate stages are largely dependent uponthe specific manner in which and the specific conditions under whicheach stage is effected and the arrangement of the'stages with respect toother necessary operations in a complete process for producing alkymer-sboiling in the range of motor fuels from readily available rawmaterials.

It has also been found that the alkymers produced from a normal olefinand an isoparafiin are of appreciable higher octane value then thosederived from the corresponding.iso-olefin and isoparaffin, and further,that a higher ultimate yield of high antiknock motor fuel of superiorquality can be produced from a given quantity of raw material containingiso-olefin, normal olefin and isoparafiin by first selectivelypolymerizing the iso-olefin and/or copolymerizing it with a portion ofthe normal olefin and then causing the remaining normal olefin toalkylate the isoparaf-. fin than can be produced from the same quantityof the. same raw material by any other sequence of steps. It has,however, at the same time been found that when a mixture containingiso-olefin, normal olefin and isoparaffin, such'as the butanebutenefraction produced during the cracking of a petroleum oil, is subjectedto the usual polymerization by the widely used polymerization cat-,alysts of the phosphoric acid typ a substantial isobutane and isobutenefrom admixture with normal butane and normal butene,'the catalyticpolymerization of said isobutene and the subsequent alkylation of saidisobutane with said normal butene whereby a maximum yield of fuel ofmaximum antiknock value is produced.

It is a more specific object of the present invention to provide aprocess comprising the selective polymerization of iso-olefin fromadmixture with the corresponding isoparafiin under conditions controlledto conserve said isoparaflin for subsequent alkylation with normalolefin.

It is another specific object of the present invention to provide aprocess for converting hydrocarbon mixtures containing isoparafiin,isoolefin, normal paramn and normal olefin into motor fuel of highantiknock value and in high yield which comprises separating theisoparaffin and iso-olefin from the normal parafiin and normal olefin,polymerizing the iso-olefin in the presence of the isoparafiin underconditions which do not result in the substantial isomerization of theisoparaffin and then alkylating said isoparafiin with said normalolefin.

It is a more specific object of the invention to provide a processwherein a butane-butene hydrocarbon fraction is fractionally distilledto separate isobutane, isobutene and l-butene from normal butane and2-butene, the separated isobutane isobutene-l-butene cut is subjected topolymerization under mild conditions whereby the isobutene and part orall of the l-butene is polymerized and removed, the normalbutane-2-butene cut is caused to alkylate a strong acid solution and thethus alkylated acid solution is used to alkylate the isobutane.

The process of the present invention will now be described withreference to the C4 or butanebutene fraction of the hydrocarbonsresulting from the liquid phase cracking of a petroleum oil, although itis to be understood that the invention is not limited thereto but may beapplied with good results to other hydrocarbon mixtures containingisoparaffins of less than six carbon atoms per molecule, correspondingnormal paraffins and corresponding isoand normal olefins or olefinscontaining a smaller number of carbon atoms per molecule. The analysisof a typical butane-butene cut is as follows:

Hydrocarbon analysis Per cent C3 and lighter 3.1 Isobutene 17.5 Normalbutenes 26.5 Isobutane 18.0 Normal butane 34.6 C5 and heavier 0.3

In a preferred embodiment of the present invention such a fraction asproduced, or usually after appropriate purification for the removal ofnitrogen and/or sulfur-containing compounds, is

Boiling points of hydrocarbons C; and lighter Below -44. 0 47. 2 10. 213.6

0 and heavier Above 9. 0 48. 2

The overhead fraction containing isobutane, isobutene and l-butene ispassed through a polymerization plant wherein it is subjected tocontrolled, mild, polymerizing conditions in the presence of anappropriate polymerization catalyst for the selective polymerization ofthe isobutene and/or its copolymerization with l-butene. The residual C4out after this polymerization operation will thus consist substantiallyof isobutane or isobutane containing a minor proportion of 1- butene.The bottoms fraction, containing the normal butane and 2-butene iscontacted with a solution of strong acid of the sulfuric acid typewhereby the butene is absorbed, producing an alkylated acid solution andthe normal butane is left as a separate phase and may thus be easilyeliminated from the system.

The alkylated acid solution so produced is then intimately contactedwith the residual C4 cut from the polymerization step in a separatehydrocarbon alkylation zone under conditions such that isobutane is inlarge excess over the organic components of the alkylated acid. Thealkylated acid solution and such l-butene as may remain in the C4 cuteffect the alkylation of the isobutane and the acid is therebyliberated. The acid and hydrocarbon layers are separated, thehydrocarbon layer is stabilized for the removal of excess isobutane fromthe alkymer product, the isobutane is returned to the hydrocarbonalkylation stage, the liberated acid is returned to the acid alkylationstage and the alkymer product is redistilled to give a fuel of desiredboiling range or is otherwise treated as may be desired.

The polymerization reaction in the polymerization plant may be effectedby means of any one of several known polymerization catalysts as, forinstance, sulfuric acid or phosphoric acid. When it is desired toselectively polymerize a portion of the isobutene and copolymerize aportion of it with L-butene, such result may be obtained by means of aphosphoric acid catalyst at temperatures between about 50 Rand 350 F.Either the so-called solid phosphoric acid catalyst prepared bycalcining a mixture of phosphoric acid absorbed in diatomaceous earth orthe film type catalyst consisting of a thin film of phosphoric acidadsorbed on the surface of an inert, non-porous solid support, such asglassy quartz, is suitable for this purpose. 'When it is desired topolymerize only the isobutene to di-isobutene, either of the above typesof phosphoric acid catalyst may be employed, holding the reactiontemperature between about 50 F. and 150 or a liquid sulfuric acidcatalyst containing about 60% to 70% H2504 may be used at a temperaturebetween about 90 F. and 130 F. I

The strong acid alkylation'catalyst employed in the alkylation stages ofthe process may be any one of several of the sulfuric acid type such asconcentrated sulfuric acid,-containing above about 90% H2804,chlorosulfonic acid, mixed sulfuric and phosphoric acids or mixedsulfuric and chlorosulfonic acids. For convenience in further explainingthe process of the present invention concentrated sulfuric acid will beemployed as the preferred example without, however, signifying that theinvention is limited thereto.

The alkylation of sulfuric acid by 2-butene takes place readily withacid of any strength above about 50% H2804 at ordinary atmospherictemperatures and the butene in either gaseous or liquid phase. The mostimportant precaution to be observed in effecting. the acid alkylationreaction is to prevent the temperature of reaction from increasing, dueto the heat liberated in the reaction, to a point at which undesirableside reactions take place to a considerable extent. It will usually befound desirable to maintain the temperature of reaction below about 100F.

The alkylation of isobutane by the alkylated sulfuric acid, on thecontrary, requires that all of several reaction conditions be fulfilledand closely maintained. For instance, it is practically necessary thatthe isobutane be in liquid phase, that the contact between isobutane andthe alkylated acid solution be extremely good, that the concentration.of butyl acid sulphate and other alkyl components in the alkylated acidbe relatively low, usually of the order of about 1%, that theconcentration of free sulfuric acid be above about 86% by weight, thatthe ratio of isobutane to total acid alkylation products be high,usually well above to 1 and that the temperature be closely controlledand maintained below about 150 F., in order to obtain a satisfactoryrate of reaction and at the same time to avoid undesirable sidereactions.

According to the process of the present invention, the acid alkylationreaction is effected in any convenient manner, such as by dispersing theacid in a body of the liquid hydrocarbon mixture, containing theZ-butene and normal butane, Or by dispersing said mixture in a body ofthe acid or by bubbling said mixture as a gas through the liquid acid.Ordinarily, it will be found most desirable for simplicity of operationand economy of equipment to eifect the acid alkylation reactionaccording to the continuous countercurrent principle wherein the liquidhydrocarbon mixture is caused to pass upwardly through a vessel ofappropriate dimensions, such as a 10 x foot unpacked cylindrical drum,while the liquid acid is dispersed from a suitable distributor placednear the top 01 said vessel, falls by gravity through the ascendinghydrocarbon phase and is collected and drawn off from the bottom of thevessel. In such a method ofoperation, the relation between thequantities of hydrocarbon and acid charged per unit of time may bevaried so as to remove substantially all of the olefin from thehydrocarbon mixture during a single passage of the acid through thecolumn under the temperature conditions most suitable to the reactionand, at the same time, to build up.

the desired concentration of alkylation products in the alkylated acid.Y

The process of this invention may, be better -'understood byreference tothe figure of the at- 'tached drawing. According 'to my preferredmethod, a hydrocarbon mixture containing olefin and both normal andisoparafli'ns, such as the above butane-butene cut, may be passedthrough line I tobutane still-2 equipped with heating element 3, whereinit is fractionated to produce an overhead distillate containingisobutane, isobutene and l-butene', and a bottom fraction containingnormal butane and 2-butene. The overhead fraction is passed through line4 and condenser 5 to receiving drum 6, from which uncondensed materialmay be vented through valve 1. Liquid condensate removed from drum 6 bypump 8 may be returned to still 2 by means of valve 9 and line H), ormay be sent forwaro through line H to'the polymerization plant l2 whichmay be of any well-known design and is hence shown only in diagram.After removalof the isobutene and a portion or all of the l-butene inthe polymerization plant, the remainder of the overhead '04 cut,containing a large proportion of isobutane, is passed through line H tomanifold 15 of the hydrocarbon alkylation stage presently to bedescribed.

The bottoms fraction from the butane still 2, containing 2-butene andnormal butane, may be removed through line i6 and passed to the acidalkylation zone H to be contacted therein with acid introduced from anappropriate distributorheader I8, whereby the 2-butene is absorbed bythe acid forming alkylated acid solution Ma and is thus separated fromthe normal butane, which may then be removed through valve; 26. Sincethe heat liberated in the acid alkylation reaction is, as previouslyindicated, sometimes quite considerable, it will usually b founddesirable to equip the acid alkylation zone I! with a cooling coil 21,which may be conveniently immersed in the alkylated acid layer Ila, asindicated. Also in the interest of temperature control in the acidalkylation reaction, it may be desirable to equip the acid feed line i9,leading to the header IS, with a temperature regulator 20 by means ofwhich to heat 'or cool the incoming acid, as may be desired. Fresh acidusually of or higher HiSOi concentration is fed to line 19 by pump 2ithrough line 22 and valve 23,,while recycled acid may be supplied bypump 24 throughline 25. as later explained.

The alkylated acid collected at Ha is led from the acid alkylation zonethrough line 28 and delivercd to manifold 15 of the hydrocarbonalkylation zone wherein it is mixed with the residual C4 overheadfraction entering from .the polymerization'plant through line l4, aspreviously mentioned. Additional isobutane ,from an external sourcemaybe introduced into manifold l5 through line 63 by means of. pump 62in order to maintain thenecessary high ratio of isobutane to acidalkylation .products. The mixture of hydrocarbon .and'acid produced inmanifold I5 is led directly into contactor 29, which may be of anyappropriate construction to give intimate contact between an aqueous andan oil phase. The reaction mixture from contactor 29 may be passedthrough a further contacting zone 30, in order to provide ample time forcompletion of the hydrocarbon alkylation reaction, and thence throughline 3| to separator 32 whereinfthe acid liberated during the alkylationreaction is separated from the. alkymer product and excess isobutane andis collected as indicated at 32a, while the hydrocarbon layer is ledthrough line 34 to the alkymer stabilizer 35. Under certain conditions,it may be desirable to return a portion of the alkymer product andexcess isobutane to manifold of the hydrocarbon alkylation zone throughvalve 65 and line 36. The liberated acid collected at 32a may bedischarged from the system through" valve 33 or returned by pump 24through line 25, cooler and line l9 to the acid alkylation. zone I1 forfurther participation in the cycle. l

In alkymer stabilizer 35, which is equipped with heating-element 66, thealkymer product is'separated from excess isobutane which passes overheadthrough line.3| and condenser 38 to receiving drum 39, while the alkymerproduct passes through line 45 and may be removed to storage throughvalve 46 or sent by means of pump 41 ,to alkymer still 48. A portion ofthe liquid isobutane collectedin drum 39 may be returned by pump 4|.through valve 42 and line 43 to provide reflux liquid in stabilizer 35,while the remainder eliminated and thus the possibility of formingundesirable alkymers'u'nder the unfavorable conditions prevailing in theacid alkylation zone is positively. avoided. Still another advantageresults from the ready elimination of normal paraffin which is madepossible byfeeding to the acid alkylation stage a mixture ofsubstantially onlynormal parafiin and normal olefin of correspending orlower molecular weight. By this means the separation of normal parafiinfrom olefin having a boiling point so close to that of the normalparaffin as to preclude practical separation bydistillation is effectedin a simple and expeditious ma'nnen I Although the best method ofapplying the process of this invention has been explained andillustrated by reference to a specific butane-butene cut, the process ofthe invention is, nevertheless, useful'for manufacturing high antiknockmotor fuel hydrocarbons from any mixture of relatively lighthydrocarbons containing isoparafiln having les than six carbon atoms permolecule, a corre sponding normal paraffin, and normal and isoolefins ofcorresponding or lower molecular weight wherein a separation byfractional distillation may be readily effected between the isoparaffinand iso-olefin on the one hand, and, on the other hand, the normalparaflin and any normal olefin having a boiling point so close to thatof the normal paraffin that it is practically impossible to separatethem by fractionation, be-

- of this invention in a broader sense embraces the manufacture of highantiknock motor fuel bydrocarbons from any relatively light hydrocarbon45 fraction containing isoparafiin, iso-olefin and norzone. Lightalkymer distillate collected in drum 52 may be returned by pump 54through valve 55 and line 56 to the alkymer still 48 or discharged fromthe system through line 51. Any gases hav ing accumulated in receivingdrum 52 may be released through the line controlled by valve 53.

One particular advantage of the process of the present invention thatmay be emphasized in summary is the separation of 2-butene fromisobutane prior to passing the latter admixed with isobutene andl-butene to the polymerization stage. By thus substantially reducing theconcentration of normal olefin in the mixture fed to the polymerizationplant and by further controlling the conditions therein to give onlyselective or copolymerization, it has been found possible to reduce theloss of isobutane from as high as 50% to 60% to well below 20% and thusto effect a very worthwhile saving of this valuable raw material.

Another advantage of the operation outlined results from feeding to theacid alkylation stage a mixture from which the isoparaffin has been malolefin by separating a portion of said normal olefin from said fractionso that the concentration of normal olefin in said fraction is reducedto minimize loss of isoparafiin when the remainder of said fraction issubjected to polymerization controlled to form polymers and minimizeloss of isoparafiin and by alkylating the isoparaffin with the separatednormal olefin in a hydrocarbon alkylation zone. been mentioned in theforegoing description as the preferred alkylation catalyst and sulfuricor phosphoric acid as the preferred polymerization catalyst, otherstrong acid alkylation catalysts of p the sulfuric acid type, of whichseveral have been named, may be employed in the alkylation stages andother selective polymerization catalysts may be used in thepolymerization reaction.

Having now fully described and explained an improved process foreffecting the reaction of hydrocarbon mixtures comprising isoparafilnsand olefins for the production of valuable hydrocarbons of highantiknock value, I claim:

1. In a process of producing a high yield of high antiknock motor fuelhydrocarbons from a mixture of relatively light hydrocarbons containingisobutane, isobutene, l-butene, Z-butene and normal butane, the. stepswhich comprise separating said mixture by fractional distillation into afirst fraction containing isobutane, isobutene and 1- butene and asecond fraction containing 2-butene Likewise, while sulfuric acid hasJected to polymerizing conditions controlled to produce polymers and tominimize loss of isobutane, separating said polymers from theunpolymerized portion of said fraction, absorbing 2-butene from saidsecond fraction in' a sulfuric acid alkylation catalyst containing aboveabout 86% by weight H2504 thus forming an alkylated sulfuric acidsolution containing butyl acid sulphate and Separating substantiallypure normal butane, and allwlating a portion of said isobutane from thesaid unpolymerized portion of said first fraction with said alkylatedsulfuric acid solution.

2. Process of producing a high yield of high antiknock motor fuelhydrocarbons from a mixture of relatively light hydrocarbons containingisobutane, isobutene, l-butene, 2-butene and normal butane, whichcomprises separating said-mixture by fractional distillation into afirst fraction containing isobutane, isobutene and l-butene and a secondfraction containing 2-butene and normal butane, passing said firstfraction to a polymerizing zone wherein said fraction is subjected topolymerizing conditions controlled to produce polymers by polymerizingisobutene and to minimize loss of isobutane, separating said polymersfrom the unpolymerized portion of said fraction, absorbing 2-butene fromsaid second fraction in an acid alkylation catalyst of the sulfuric acidtype thus alkylating said acid and forming an alkylated acid solutionand a separate hydrocarbon phase containing normal butane, andalkylating a portion of said isobutane from the said unpolymerizedportion of said first fraction with said alkylated acid solution.

3. Process of producing a high yield of high antiknock motor fuelhydrocarbons from a mixture of relatively light hydrocarbons containingisobutane, isobutene, 1,-butene, 2-butene and normal butane, whichcomprises separating said mixture by fractional distillation into afirst fraction containing isobutane, isobutene and 1- butene and asecond fraction containing 2- butene and normal butane, passing saidfirst fraction to a polymerizing zone wherein said fraction is subjectedto polymerizing conditions controlled to produce polymers bypolymerizing isobutene and copolymerizing isobutene and 1- butene and tominimize loss of isobutane, separating said polymers from theunpolymerized portion of said fraction, absorbing Z-butene from saidsecond fraction in an acid alkylation catalyst of the sulfuric acid typethus alkylating said acid and forming an alkylated acid solution and aseparate hydrocarbon phase containing normal butane, and alkylating itleast a portion of said isobutane from the said unpolymerized portion ofsaid first fraction with said alkylated acid solution in the absence ofnormal butane.

4. Process of producing a high yield of high antiknock motor fuelhydrocarbons from a mixture of relatively light hydrocarbons containingisobutane, isobutene, l-butene, 2-butene and normal butane, whichcomprises separating said mixture by fractional distillation into afirst fraction containing isobutane, isobutene and 1- butene and asecond fraction containing 2- butene and normal butane, passing saidfirst fraction to a polymerizing zone wherein said first fraction issubjected to polymerizing conditions controlled to produce polymers andto minimize loss of isobutane, separating said polymers from theunpolymerized portion of said fraction, absorbing 2-butene from saidsecond fraction in an acid alkylation catalyst of the sulfuric acid typethus alkylating said acid and forming an alkylated acid solution and aseparate hydrocarbon phase containing normal butane and alkylating atleast a portion of said isobutane from the said unpolymerized portion ofsaid first fraction with said alkylated acid solution.

5 Process of manufacturing high antiknock motor fuel hydrocarbons from amixture of relatively light hydrocarbons containing normal butane,isobutane, isobutene, l-butene and 2- butene, which comprises separatingnormal butane and 2-butene from said mixture by fractional distillation,passing the remaining mixture containing isobutene, l-butene andisobutane to a polymerizing zone wherein said remaining mixture issubjected to polymerizing conditions controlled to produce polymers andto minimize loss of isobutane, separating said polymers from theunpolymerized portion of said remaining mixture, absorbing 2-butene fromnormal butane in an excess of alkylation catalyst capable of absorbingsaid 2-butene and thereby forming an alkylated catalyst solutioncontaining an excess of catalyst and separating therefrom normal butane,passing said unpolymerized portion of said remaining mixture and saidalkylated catalyst solution containing an excess catalyst to analkylation zone wherein isobutane is aikylated.

6. In a process of producing a high yield of high antiknock motor fuelhydrocarbons from a butane-butene cut containing isobutane, isobutene,normal butane, l-butene and 2-butene, the steps which comprisefractionally distilling said out to produce an overhead fractioncontaining isobutane, isobutene and l-butene and a bottoms fractioncontaining 2-butene and normal butane, contacting said bottoms fractionwith sulfuric acid containing above about 86% by weight H2804 in an acidalkylation zone forming an alkylated acid solution containing butyl acidsulphate by reaction of said 2-butene with said sulfuric acid and thusseparating the normal butene from said normal butane, passing saidalkylated acid solution to a hydrocarbon alkylation zone separate fromsaid acid alkylation zone, passing said overhead fraction containingisobutane, isobutene and l-butene to a polymerization zone whereinconditions are controlled to produce polymers and minimize loss ofisobutane, separating said polymers from the unpolymerized portion ofsaid overhead fraction and passing said unpolymerized portion containingisobutane to said hydrocarbon alkylation 1 zone, intimately contactingsaid isobutane with said alkylated acid solution in said hydrocarbonalkylation zone, passing the resulting reaction mixture to a separatingzone. wherein sulfuric acid is separated from hydrocarbons, returning aportion of said separated hydrocarbons to said alkylation zone,returning a portion of said separated sulfuric acid to said acidalkylation zone, passing the remaining portion of said hydrocarbonsseparated from said sulfuric acid in said separating zone to astabilizing zone wherein isobutane is distilled from alkymer product,condensing said isobutane and returning a portion thereof to saidhydrocarbon alkylation zone, passing said alkymer product from saidstabilizing zone to an alkymer product still and therein distilling fromsaid alkymer product a desired motor fuel fraction.

7. In a process of producing a high yield of high antiknockimotorriuelhydrocarbons from a butane-butene cut containing iisobutane, isobutene,normal butane, l-butene and Z-Ybutene, the steps which comprisefractionally distilling said out to produce an overhead fractioncontaining isobutane, isobuteneand l-butene and a bottoms fractioncontaining 1 Z-butene and normal butane, contacting said bottomsfraction with sulfuric acid containing above about 86% by weight in anacid ialkylation zone forming an valkylatedacid solution containingbutyl acid sulphate by reaction of said 2-butene with said sulfuric acidand ithus'separating the normal butene'irom said normal butane, passingsaidalkylated acid solutionito a hydrocarbon alkylation zone separatefrom said acid .alkylation zone, passing said overhead fractioncontaining isobutane, isobutene'and l-butene to a polymerizationzonewherein conditions are controlled to 'produceppolymers-and minimizeloss of isobutane, separating said'polymers from the unpolymerizedportion of said overhead fraction and passing said unpolymerized portioncontaining isobutane to said hydrocarbon alkylation zone, whereinisobutane is 'alkylated by intimately contacting said isobutane withsaid alkylated acid solution in said hydrocarbon alkylation zone,passing the resulting reaction mixture to a separating zone whereinsulfuric acid is separated from hydrocarbons, passing said hydrocarbonsseparated from said sulfuric acid in said separating zone to astabilizing zone wherein isobutane. is distilled from alkymer product,con- Y densing said isobutane and returning a portion thereof to saidhydrocarbon alkylation. zone, passing said alkymer product fromsaidstabilizingzone to an alkymer product still and therein distilling fromsaid alkymer product a desired motor fuel fraction.

OTIO N. MILLER.

